Overload control valve

ABSTRACT

A valve for controlling the maximum pressure of gas in a system has a control chamber which senses pressure in the system through an aperture that extends lengthwise of a spring-pressed valvepiston which is moved to cutoff position by excess pressure.

United States Patent Inventor John M. Barosko Kenosha, Wis. Appl. No. 828,470 Filed May 28. 1969 Patented Feb. 2, 197] Assignee Tenneco Inc.

Houston, Tex. a corporation of Delaware. by mesne assignments OVERLOAD CONTROL VALVE 10 Claims. 3 Drawing Figs.

US. Cl 137605.13, 137/470, 137/505.28 Int. Cl Fl6k 31/143 Field of Search ..137/505.13, 505.28. 470

1927 VIA 1 *4/ [56] References Cited UNITED STATES PATENTS 683.388 9/1901 Curtis 127/505/28X 1,294,151 2/1919 Page .1 137/505.28X 1.962549 6/1934 Bjorklund 137/5051 3X 2,027,762 1/1936 Becker............ 137/505.13X

Primary Examinerl-larold W. Weakley AllorneyHamess, Dickey & Pierce ABSTRACT: A valve for controlling the maximum pressure of gas in a system has a control chamber which senses pressure in the system through an aperture that extends lengthwise of a spring-pressed valve-piston which is moved to cutoff position by excess pressure.

if Z [j if OVERLOAD CONTROL VALVE BRIEF SUMMARY OF THE INVENTION It IS the purpose of this invention to provide a nonventing control valve adapted for use with air (or gas) operated devices to control maximum pressure.

The invention accomplishes this by means of a structure in which a housing has a through flow chamber with a shutoff valve seat at one end of a slidable valve-piston and a nonventing control chamber at the other end. A passage through the valve-piston connects the two chambers. The design features enable the control chamber pressure to closely follow that in the outlet side of the flow chamber thereby providing for accurate operation of the valve.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an air operated automobile lift device having a control valve in the air supply line which is constructed in accordance with this invention;

FIG. 2 is an enlarged longitudinal cross section through the control valve of FIG. 1; and FIG. 3 is an enlarged cross section through the roll pin of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The overload control valve 1 has a housing 3 which is composed of an air passage section 5 arid a piston-valve cylinder section 7 which is threaded into a portion of the section 5 as indicated at 9. The air passage section has an internally threaded inlet 11 and an internally threaded outlet 13 which are connected by a flow through chamber 15 that includes a valve seat 17. A valve-piston structure 19 is slidable in the housing section 7 and at excessive pressures in outlet 13 engages the valve seat 17 to cutoff flow between the inlet 11 and the outlet 13.

A typical installation and application is illustrated in FIG. 1 wherein the lift or jack 21 has a vertical housing 23 which includes air pressure operated elements (not shown) receiving air through the conduit 25 which is threaded into the outlet section 13 of the valve element 1. The valve 1 receives air from a conduit 27 which is threaded into the inlet 11 and is itself connected to a hand-operated shutoff valve 29 that receives air under pressure from the supply line 31.

In operation, when the hand valve 29 is opened and pressures are below the setting of the control valve 1, airunder pressure will flow from the supply line 31 through the hand valve 29 into the conduit 27 to reach the valve 1. It flows through valve chamber 15, by the valve seat 17 into the conduit 25 and then into the lift device 21. In the event that excessive pressures develop, the valve-piston 19 will seat on the valve seat 17 and cut off flow from the conduit 27 to the conduit 25. Two particular advantages of the structure of the valve 1 are first, it is closely responsive to the pressure in the device 21; and, second, it does not blow off or vent air and therefore does not decrease pressure in the lift device 21 which could cause a lowering of the load being lifted.

The foregoing advantages are provided by the particular structure of the piston 19 and its component parts in conjunction with the arrangement of a control chamber and a sensing chamber. The piston-valve 19 includes a valve head section 33 that carries a seal 37, held in place by an enlarged end portion 39, which is shaped to seat and seal on the valve seat 17. The valve section 33 has an internal aperture which receives the outer diameter of a piston stem 41 and is secured to it by the transverse tubular roll pin 43 extending through aligned apertures in the two parts. The slot 43A in the roll pin 43 forms a transverse passage connecting an annular sensing chamber 45 with a longitudinal passage 47 that extends through the entire length of the stem 41 including the piston portion 51 of the valve-piston member 19. It will be seen that the annular pressure sensing chamber 45 communicates with the outlet 13 through the flow chamber 15 and is substantially larger than the outer diameter of the valve head 33. The opposite ends of the roll pin slot 43A open into the annular chamber 45 at remote and protected positions with respect to the inlet 11 to the chamber 15 and are therefore subjected to a minimum inlet pressure effect. The slot 43A in the roll pin 43 also provides a restriction that prevents pressure in the passage 47 from building up faster than pressure at the outlet 13.

An adjustable nut 53 is threaded at 55 into the end of the housing cylinder section 7 and has a recess 57 formed in its inner end to provide a control chamber 59. The inner end of the nut 53 has a valve seat 61 which is engaged by a seal 63 (which is preferably identical to seal 37) that is held in place by an enlarged end section 65 on the piston section 51. The inside face of the seal 63 is held against a shoulder 66 on the piston end 51 so that the seals 37 and 63 serve as valve means at opposite ends of the valve-piston member 19. The section 51 has a land 67 which acts as a piston portion to slide in the bore 68 of housing section 7 and the side thereof facing chamber 59 supports the base of a U-shaped resilient annular packing cup 69 which opens toward the chamber 59.

An adapter and stem support 73 fits in a recess 75 in the housing 5 and is held against the bottom thereof by the inner end of the section 7. It has a through opening 76 the wall of which engages and supports the stem 41 of the valve member 19. Sealing of the sliding joint is provided by a U-shaped resilient annular packing cup 77 that fits in a groove 79 in the adapter 73 and is arranged to open toward the annular chamber 45. An O-ring 80 in groove 81 seals the nut 53. It is noted that U-cups in the sliding joints are used instead of other seal forms, such as O-rings, as they give better sensitivity to the valve. The U-cups face outwardly of the variable size chamber containing the valve spring 83 and in opposite directions and can flex to preclude internal pressure lockup in the spring chamber.

The coil spring 83 bears at one end against the adapter 73 (that is against shoulder 75 of housing 5) and at' its other end against the face 85 of the piston land 67, being guided by the enlarged diameter 87 on the piston portion 51. The spring 83 holds the seal 63 on seat 61 when pressures at the outlet 13 are less than the setting of the valve as determined by the precompression of the spring. This can be adjusted by varying the longitudinal position of the nut 53 which has wrench recesses 89 in its outer face to provide for rotation and threaded movement longitudinally of the cylinder 7. A snap plug 91 may be used for closing the outer end of the housing section 7 adjacent the nut.

The control chamber 59 is connected to sensing chamber 45 by the passage 47 and roll pin 43. Thus, when pressure builds up in chamber 45 above a level determined by the setting of spring 83, the valve-piston 19 will be forced to the left so that the seal 63 leaves the seat 61 whereupon pressure will reach the larger diameter provided by the land 67 of the piston head 51 and the valve member 19 will be forced rapidly to the left to seat the seal 37 on the seat 17 and shutoff flow. The higher pressure at inlet 11 will then be directly on the exterior of valve head 33 and will be passed through roll pin 43 and passage 47 to control chamber 59 and serve to hold the valve-piston 19 in shutoff position until the inlet pressure is reduced sufficiently to allow the spring 83 to reseat seal 63 on seat 61.

As indicated, the construction is such that the pressure in the control chamber 59 is close to that at the outlet and is substantially isolated from inlet pressure effects thereby insuring proper response of the valve to the pressure conditions within the device 21. Since there is no venting of the pressure when the valve member 19 is seated on the valve seat 17, the pressure within the device2l will be maintained so that there is no danger of lowering of a load that may be carried by it due to operation of the overload valve 1.

I claim:

1. An overload control valve comprising a housing having a fluid inlet and a fluid outlet and a fluid flow chamber connecting said inlet and outlet, a first valve seat in said flow chamber between said inlet and outlet arranged so that all fluid flows through the seat when the valve is open. said housing including a bore and first seal means defining one end of the bore. said housing including a pressure sensing chamber located between said seal means and said flow chamber and out of the path of fluid flow from said inlet to said outlet. said housing having control chamber forming means at the outer end of the bore and including a second valve seat, said first and second valve seats and said bore and chambers being longitudinally aligned a longitudinally movable valve piston member in said bore having first and second valve portions at opposite ends arranged to seat respectively on said first and second valve seats and including a valve stem slidably extending through said seal means and an enlarged piston portion slidably engaging the wall of said bore. second seal means associated with said piston portion and engaging the wall of the bore. resilient means urging said valve member to seat on the second valve seat, said valve member including a longitudinal aperture in said stem and opening out of said second valve portion into said control chamber when said valve member is seated on said second valve seat, said valve member including transverse aperture forming means at the first valve portion end opening into said sensing chamber and connecting said sensing chamber to said longitudinal aperture when said valve member is seated on said second valve seat, said longitudinal aperture and said control chamber communicating with said piston portion when said valve member is unseated from said second valve seat and the pressure therefrom acting on the piston portion in a direction to seat said first valve portion on said first valve seat.

2. A valve as set forth in claim 1 including a coil spring in said bore based at one end on said first seal means and the other end bearing against a side of said piston portion, said coil spring forming said resilient means.

3. A valve as set forth in claim 2 wherein said control chamber forming means is longitudinally adjustable in said housing to vary the compression of said coil spring.

4. A valve as set forth in claim 1 wherein at least one of said seal means is flexible to provide for relief of pressure in the bore on the low-pressure side of the piston portion.

5. A valve as set forth in claim 4 wherein said one seal means comprises a U-cup element.

6 A valve as set forth in claim 1 wherein said first valve portion comprises a separate element mounted on said stem and said transverse aperture forming means comprises a slotted roll pin securing the element to the stem.

7. A valve as set forth in claim 6 wherein said resilient means comprises a coil spring in said bore confined between said first seal means and the low pressure side of said piston portion.

8. A valve as set forth in claim 7 wherein said one of first and second seal means comprises an annular U-cup facing outwardly from the adjacent end of the coil spring.

9. A valve as set forth in claim 8 wherein both said seal means comprise annular U-shaped cups facing outwardly from the adjacent end of the coil spring.

10. A valve as set forth in claim 9 wherein the control chamber forming means is longitudinally adjustable in said housing to vary the compression of the coil spring. 

1. An overload control valve comprising a housing having a fluid inlet and a fluid outlet and a fluid flow chamber connecting said inlet and outlet, a first valve seat in said flow chamber between said inlet and outlet arranged so that all fluid flows through the seat when the valve is open, said housing including a bore and first seal means defining one end of the bore, said housing including a pressure sensing chamber located between said seal means and said flow chamber and out of the path of fluid flow from said inlet to said outlet, said housing having control chamber forming means at the outer end of the bore and including a second valve seat, said first and second valve seats and said bore and chambers being longitudinally aligned, a longitudinally movable valve piston member in said bore having first and second valve portions at opposite ends arranged to seat respectively on said first and second valve seats and including a valve stem slidably extending through said seal means and an enlarged piston portion slidably engaging the wall of said bore, second seal means associated with said piston portion and engaging the wall of the bore, resilient means urging said valve member to seat on the second valve seat, said valve member including a longitudinal aperture in said stem and opening out of said second valve portion into said control chamber when said valve member is seated on said second valve seat, said valve member including transverse aperture forming means at the first valve portion end opening into said sensing chamber and connecting said sensing chamber to said longitudinal aperture when said valve member is seated on said second valve seat, said longitudinal aperture and said control chamber communicating with said piston portion when said valve member is unseated from said second valve seat and the pressure therefrom acting on the piston portion in a direction to seat said first valve portion on said first valve seat.
 2. A valve as set forth in claim 1 including a coil spring in said bore based at one end on said first seal means and the other end bearing against a side of said piston portion, said coil spring forming said resilient means.
 3. A valve as set forth in claim 2 wherein said control chamber forming means is longitudinally adjustable in said housing to vary the compression of said coil spring.
 4. A valve as set forth in claim 1 wherein at least one of said seal means is flexible to provide for relief of pressure in the bore on the low-pressure side of the piston portion.
 5. A valve as set forth in claim 4 wherein said one seal means comprises a U-cup element.
 6. A valve as set forth in claim 1 wherein said first valve portion comprises a separate element mounted on said stem and said transverse aperture forming means comprises a slotted roll pin securing the element to the stem.
 7. A valve as set forth in claim 6 wherein said resilient means comprises a coil spring in said bore confined between said first seal means and the low pressure side of said piston portion.
 8. A valve as set forth in claim 7 wherein said one of first and second seal means comprises an annular U-cup facing outwardly from the adjacent end of the coil spring.
 9. A valve as seT forth in claim 8 wherein both said seal means comprise annular U-shaped cups facing outwardly from the adjacent end of the coil spring.
 10. A valve as set forth in claim 9 wherein the control chamber forming means is longitudinally adjustable in said housing to vary the compression of the coil spring. 